Battle of Cengshan

The Battle of Cengshan occurred in 291 AD when the army of Sima Yue, the Prince of Donghai, defeated the army of Sima Zhi, the Prince of Pengcheng as it threatened Sima Yue's home base of Donghai Commandery.

Background
In 291 AD, following the death of the Jin emperor Sima Yan and the accession of Sima Zhong to the throne, the princes of the Sima clan vied for the title of Regent. In addition to the main Sima clan princes, minor Sima princes also took part in the struggles. Sima Zhi, the Prince of Pengcheng, took up arms against the Prince of Donghai, Sima Yue, and, in doing so, rebelled against the Emperor. Sima Yue responded by preparing an army to crush his rebellious kinsman, and Sima Zhi sent his general Luo Luban with 481 troops to march on Donghai.

Battle
Sima Yue and his general He Lun marched out of Donghai with their own army of 782 troops, attacking the invading army sent by the traitor Sima Zhi. The two armies met along the border of Pengcheng and Donghai Commanderies near the farming town of Cengshan, and the battle began when Luo Luban challenged He Lun to a duel. They fought to a draw as the two armies clashed, with Sima Yue's larger army attacking the enemy's flanks as well as their front, overwhelming them. Eventually, noticing that He Lun was unable to beat Luo Luban by himself, Sima Yue interrupted the battle by joining He Lun in fighting him, and the two of them slew Luo Luban. Sima Yue's army pursued and slaughtered Sima Zhi's army, annihilating it and taking 84 prisoners, who were then recruited into Sima Yue's own army.